This invention relates generally to a biopsy instrument; a device for removing a sample of tissue from a human being or an animal. More particularly, the invention relates to an automated biopsy instrument in which an outer cannula is driven over an inner stylet to obtain the tissue sample.
The procedure known as biopsy, or the removal of samples of human and animal internal tissue, has been for many years a favored method for the nonsurgical diagnosis of tissue. Using biopsy needles one can take out samples from deeply located organs, such as the liver or the kidneys. This kind of sampling, is usually carried out in such a way that a doctor inserts a needle assembly through the skin and to the desired sampling location. Several kinds of biopsy needles are employed to biopsy the internal organs. One of the most commonly used needle assemblies comprises a slidably provided inner needle within a hollow outer needle. Using this kind of instrument, sampling has been performed in a two-step manual technique in which the outer hollow cutting cannula telescopically receives the inner stylet which is slidable between retracted and extended positions relative to the cannula. The sylet contains a specimen receiving slot near its sharpend distal end. In performing the first step of the technique, the physician places the tip of the needle (with the stylet retracted inside the cannula) against the tissue mass to be sampled and manually drives the stylet forward into the tissue mass. To carry out the second step, the physician manually drives the cutting cannula forwardly over the stylet, thereby severing a tissue sample and retaining it within the stylet slot inside the cannula""s hollow interior. Then the entire needle assembly containing the collected tissue sample is withdrawn, whereafter the sample can be taken out and analyzed.
Examples of manually operated biopsy needles of this general type are disclosed in U.S. Pat. No. 4,700,014, issued Jul. 15, 1986 to D. Beraha for xe2x80x9cTransrectal Prostate Biopsy Device and Methodxe2x80x9d, and U.S. Pat. No. 3,477,423, issued Nov. 11, 1969 to L. K. Griffith for xe2x80x9cBiopsy Instrumentxe2x80x9d. Actually many physicians utilize a TRU-CUT(copyright) biopsy needle available from Travenol Laboratories, Inc. of Deerfield, Ill. that is described in above mentioned U.S. Pat. No. 3,477,423 to Griffith.
Such manually operated two-step devices are awkward to manipulate, and the tissue samples obtained may often be unsatisfactory. The depths to which the stylet and the cannula are driven into the tissue mass must be carefully controlled for accuracy and efficiency. Caution is required, as well, in applying the force with which the stylet and the cannula are plunged forward. Too little force may not sever the tissue sample from the mass. Too much force may cause unnecessary damage to the surrounding vital tissues.
Several automated biopsy instruments have been invented to improve the manual procedure and make it easier. The inventive idea resides in placing the needle assembly in a box, in which box there are provided propelling means for propelling the outer and/or inner needles, such that they carry out the above mentioned coordinated movements when the needle assembly has been located to the correct sampling position in the body. The needles are brought to carry out the desired movements in that the operator actuates a release mechanism outside of the box. The example of the automated devices are seen in U.S. Pat. No. 4,767,684, issued May 26, 1987 to H. G. Leigh for xe2x80x9cBiopsy Devicexe2x80x9d. It discloses a movable stylet telescopically received in a hollow movable cannula, both the stylet and the cannula being mounted to hubs within a pistol-style grip. In use the stylet is first manually advanced into the tissue and the cannula is then driven over the stylet by depressing a trigger.
A similar instrument designed by D. N. Mehl, through U.S. Pat. No. 4,733,671, issued Mar. 29, 1988, includes a pistol-style squeezable hand grip for single hand operation. A spring tensioned sliding cannula, including a configured cutting edge, actuates by a squeeze trigger and cam arrangement to slide over a fixed position stylet for entry into a tissue sample area.
Another automated device is found in U.S. Pat. No. 4,799,154, issued Oct. 13, 1987 to P. G. Lindgren for xe2x80x9cTissue Sampling Devicexe2x80x9d. It is composed of a mechanism in which a release button is depressed to cause a spring-loaded stylet to be advanced into the tissue mass. The forward movement of the stylet also triggers the delayed release of a spring-loaded outer cannula, which slides over the stylet to sever the tissue sample.
U.S. Pat. No. 4,924,878, issued May 15, 1990 to J. E. Nottke for xe2x80x9cActuating mechanism for biopsy needle xe2x80x9d and U.S. Pat. No. 4,958,625, issued Sep. 25, 1990 to J. S. Bates for xe2x80x9cBiopsy needle instrumentxe2x80x9d, disclose two other automated devices with sequential movement of the needles.
In any event, the various automated biopsy instruments presently known tend to be heavy and difficult to manipulate. Such limitations diminish the physician""s control over the instrument and the precision with which biopsies may be performed. These instruments may be subject to inadvertent movement or torque which may, in turn, subject the patient to unnecessary trauma and risk.
Extensive bleeding can occur as a result of tissue resecting, which can lead to dangerous bleeding and complications. The idea of creating this device arrose after a complicated liver biopsy procedure. The patient developed exsanguinating blood loss through the peritoneum which led to an emergency laparatomy. This complication might be seen in tissue sampling of the visceral organ and is especially encountered in patients with bleeding diathesis. In an effort to remedy these problems, various techniques have been developed. For example, U.S. Pat. No. 3,598,108, issued Aug. 10, 1971 to K. Jamshidi for xe2x80x9cBiopsy technique and biopsy devicexe2x80x9d, discloses a biopsy technique and device involving the insertion of a biopsy needle into the tissue from which the specimen is to be taken, the needle having a sleeve member and the stylet therein, the stylet being removed and the biopsy being collected in the sleeve which is also thereafter removed. A heat transfer means such as a microcauter or a cryoprobe is inserted through the needle to project from the distal end thereof, which serves to cauterize the biopsy track as the needle and heat transfer means are removed as a unit.
In addition, U.S. Pat. No. 5,928,163, issued Jul. 27, 1999 to T. W. Roberts for xe2x80x9cBiopsy samplerxe2x80x9d, discloses a xe2x80x9chotxe2x80x9d biopsy procedure, using surgical forceps in which the jaws are electrodes (bipolar or monopolar). After the tissue sample is resected, the forceps are brought in contact with tissue remaining at the resecting site and RF energy is applied to the forceps to cause current to flow (i.e., cauterization) through the resecting site tissue to coagulate the tissue and stop the bleeding. Often, RF energy is applied to the forceps during resecting to help cut the tissue sample as well.
U.S. Pat. No. 5,810,806, issued Sep. 22, 1998 to M. A. Ritchart for xe2x80x9cMethods and devices for collection of soft tissuexe2x80x9d, employs a combination of an electrosurgical cutting and a vacuum retrieving element, for sampling tissues.
U.S. Pat. No. 5,607,389, issued Mar. 4, 1997 to Edwards, et al. for xe2x80x9cMedical probe with biopsy styletxe2x80x9d discloses several instruments for tissue collection. One of those embodiments includes a biopsy knife device in conjunction with an electromagnetic emitter for selective tissue sampling and electromagnetic heat ablation, or both.
U.S. Pat. No. 6,036,656, issued Mar. 14, 2000 to Slater, et al. for xe2x80x9cjaw assembly having progressively larger teeth and endoscopic forceps instrument incorporating samexe2x80x9d shows a design of an endoscopic forceps coupled to an electrocautery voltage supply for electrocoagulation of the biopsied tissue. Also U.S. Pat. No. 5,458,598, issued Oct. 17, 1995 to Feinberg for xe2x80x9ccutting and coagulating forcepsxe2x80x9d discloses another type of forceps coupled with an electrocautery device for coagulating tissue after taking the biopsy sample.
All of these patents, incorporated herein by reference, and others, disclose typical prior art techniques and apparatus for gathering and removing a biopsy sample of tissue for further examination and review by a trained professional.
The present invention is a further improvement in a biopsy sampling instrument, which is specially suited for viseral organ biopsies. Through the use of novel pneumatic controlling structure combined with electrocautery coagulation, the phsician can take out samples from deeply located organs easier and safer.
In one aspect, the invention features an assembly for taking a biopsy sample from a site within the body of a patient. The assembly includes a housing, which can be placed over a bed-side table and contains the biopsy needle actuator, a connection port and internal switches for appliance of an electrocautery device, a connection port and an external pedal switch for firing the actuator and a connection to the proximal end of a biopsy needle assembly. This housing not only provides the driving force for moving the stylet and the cannula forward in sequential manner, but also, it draws the needles back in to their initial (resting) position within the guide tube, after tissue sampling.
The needle apparatus includes a flexible probe that is composed of three components. A flexible plastic guide tube, which will be placed in the hand of the physician and can be guided to a point from which a sample is required. A moving cannula is telescoped within the guide tube and a notched sampling stylet is telescoped within the cannula. The tip of the stylet projects slightly from the distal end of the guide tube in percutaneous types of the needle to permit an easy penetration of intervening tissue by the sharpend tip of the sylet (e.g. subcutaneous tissue) prior to sampling. Indeed this penetration is not necessary in endoscopic type.
From another aspect, the employment of an electrocautery element in one preferred embodiment serves to cauterize the biopsy track before the needle is removed from the biopsied tissue after biopsy taking. Accordingly, the metal cannula and stylet are connected to a monopolar electrocautery device and the current is applied just after severing the tissue by forward movement of the cannula over the stylet in the tissue. Synchronizing the electrocautery appliance with the biopsy taking procedure produces electrocoagulation in the biopsy track before the needles are withdrawn. The electrical current applied to the surrounding tissue will not affect the sample tissue inside the hollow cannula due to good electrical and heat dissipation of the metal needles.
The advantages of the novel Automated Hot Biopsy Needle and Device over previous automated biopsy instruments include:
1. The housing of the majority of automated biopsy devices are grasped during the biopsy procedure. Therefore it is difficult to manipulate them especially in precise sampling. In this invention, the probe rather than housing would be grasped and manipulated by the physician, accordingly it would be easier for a physician to handle and manipulate a flexible probe especially in those situations that require high precision.
2. The biopsy needle actuator is fired by a pedal switch. This not only decreases the inadvertent movement of the needle location during biopsy taking, but also allows the physician to hold the probe with one hand while the other hand could be used to guide the probe for better localization (e.g. prostate biopsy) or to hold other instruments (e.g. laparascope or endoscope).
3. The present invention also includes a safety mechanism for preventing the accidental firing of the biopsy actuator. The safety mechanism includes an electronic timer based electrical switch on the front panel of the housing. Triggering of the biopsy actuator by firing buttons is only permitted during 20 seconds after pushing of the releasing activator button on the front panel of the housing. This period is also announced by a beeper.
4. In automated biopsy needle instruments, manual or spring loaded forward movement of the stylet into the tissue is followed sequentially by the release of spring loaded cannula for core sampling. In these devices the speed of sequential movement of the stylet and the cannula are fixed and relate to the spring force and the structural design of the instrument. The speed of forward movement of the stylet and the cannula can be adjusted in this device according to the tissue consistency. For example the speed of movement could be decreased in soft organs with low elasticity (e.g. liver) to decrease unnecessary damage to the surrounding tissue or inceased in more compact or elastic tissue to decrease the chance of unsatisfactory sampling.
5. The depth of biopsy can not be accurately predetermined by the majority of automated biopsy devices. In this technique and device the distance of the invasion of the biopsy needles from surface can be precisely predetermined.
6. This biopsy assembly can be used with conventional rigid or flexible endoscopes (i.e. laparascope, pleuroscope or other endoscopic procedures that need deep tissue biopsies).
7. Coupling an electrocautery device with the sampling procedure decreases the chance of bleeding complication. This not only decreases the bleeding risk and blood loss in usual biopsy procedures, but also makes the device useful in special circumstances (biopsy in bleeding diathesis or highly vascular organs).
Through use of this technique and device, biopsy specimens may be obtained easier, safer and more precisely. It also permits the physician to perform biopsies in patients with high risk of bleeding (e.g. bleeding diathesis, liver cirrhosis) or of those organs that bleed profusely after sampling (e.g. Spleen).